sshtools: 非交互 SSH 工具集（golink / goscp）

golink: 一条命令在远端执行，退出码原样透传，从不提示、不分配终端。
goscp:  用 SCP 协议上传，-files 一个参数同时接受文件和目录。

- 纯 Go，唯一依赖 golang.org/x/crypto，可离线交叉编译到六个桌面平台
- internal/sshx 统一建连、认证（password + keyboard-interactive）与主机密钥策略
- smoketest/ 自带迷你 sshd，57 项端到端测试（golink 38 + goscp 19）

build.sh

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+#
+# Cross-compile the sshtools binaries for the three desktop platforms.
+#
+#   ./build.sh          cross-compile every program and target
+#   ./build.sh local    only the host binaries, at dist/golink and dist/goscp
+#
+# Everything is pure Go (CGO disabled), so no cross toolchain is needed and the
+# build works offline: the only dependency, golang.org/x/crypto, is already in
+# the local module cache.
+
+set -euo pipefail
+cd "$(dirname "${BASH_SOURCE[0]}")"
+
+version="${VERSION:-1.0.0}"
+export CGO_ENABLED=0
+export GOCACHE="${GOCACHE:-$PWD/.gocache}"
+export GOFLAGS="${GOFLAGS:--mod=mod}"
+
+ldflags="-s -w -X main.version=$version"
+programs="golink goscp"
+targets="linux/amd64 linux/arm64 darwin/amd64 darwin/arm64 windows/amd64 windows/arm64"
+
+mkdir -p dist
+
+build() { # <program> <goos> <goarch> <output>
+  GOOS="$2" GOARCH="$3" go build -trimpath -ldflags "$ldflags" -o "$4" "./cmd/$1"
+  printf '  %-32s %7s  %s\n' "$4" "$(du -h "$4" | cut -f1)" "$(file -b "$4" 2>/dev/null | cut -c1-58)"
+}
+
+hostos="$(go env GOOS)"
+hostarch="$(go env GOARCH)"
+
+if [ "${1:-all}" = local ]; then
+  for program in $programs; do
+    ext=""
+    [ "$hostos" = windows ] && ext=".exe"
+    build "$program" "$hostos" "$hostarch" "dist/${program}${ext}"
+  done
+  exit 0
+fi
+
+echo "sshtools $version"
+for program in $programs; do
+  for target in $targets; do
+    os="${target%%/*}"
+    arch="${target##*/}"
+    ext=""
+    [ "$os" = windows ] && ext=".exe"
+    build "$program" "$os" "$arch" "dist/${program}_${os}_${arch}${ext}"
+  done
+done
+
+# convenience copies for the machine running this script
+ext=""
+[ "$hostos" = windows ] && ext=".exe"
+for program in $programs; do
+  native="dist/${program}_${hostos}_${hostarch}${ext}"
+  if [ -f "$native" ]; then
+    cp "$native" "dist/${program}${ext}"
+  fi
+done
+
+echo
+( cd dist && sha256sum golink_* goscp_* > SHA256SUMS && cat SHA256SUMS )